# How to adjust sewing machine tension

Source: https://stitchandhem.co.uk/blog/how-to-adjust-sewing-machine-tension
Published: 2026-10-12
Publisher: Stitch and Hem

**In short:** First rethread both threads and fit a new needle, because most tension faults are threading faults. Then sew a test seam with different coloured threads on top and in the bobbin. If bobbin thread shows on top, lower the upper tension number; if upper thread loops underneath, raise it. Change the dial one step at a time and test again.

Tension is the balance between the pull on the upper thread and the pull on the bobbin thread. When it is right, the two threads lock in the middle of the fabric and the stitch looks the same on both sides. When it is off, you see dots of the wrong colour, loops or puckering. The upper tension dial is easy to adjust, but it is also the control people turn first when the real cause is something else. This guide shows how to read the stitch, test properly and adjust in the right order.

## What balanced tension looks like

In a balanced straight stitch the upper and bobbin threads interlock between the layers of fabric, so you see only upper thread on the top and only bobbin thread underneath. If the upper tension is too tight, it pulls the bobbin thread up, and small dots of bobbin thread appear on the top surface. If the upper tension is too loose, the upper thread is pulled down and shows as loops or a ladder on the underside.

Seams that pucker or gather along their length can also mean the tension is too tight for a light fabric, although stitch length, needle size and presser foot pressure play a part as well.

## Before you touch the dial: rule out threading

Most so-called tension problems are threading problems. If the upper thread has missed the tension discs or the take-up lever, no setting will correct it. Before adjusting anything, work through these checks; if you have a tangle of loops underneath, read our guide to [thread bunching under the fabric](https://stitchandhem.co.uk/blog/thread-bunching-under-fabric) first.

1. Remove the upper thread and rethread with the presser foot up and the take-up lever at its highest point.
2. Take out the bobbin, check it is evenly wound, the correct type and inserted in the direction shown in your manual.
3. Fit a new needle that suits your fabric and thread. Our [needle size guide](https://stitchandhem.co.uk/tools/needle-size-guide) can help.
4. Use the same good quality thread on top and in the bobbin for the test.
5. Clean lint from the bobbin area, as packed fluff can change how the bobbin thread feeds.

## Test stitching in two colours

Thread the top with one colour and the bobbin with a clearly different colour, such as red over blue. Use two layers of the fabric you intend to sew, not a random scrap, because tension behaves differently on thin cotton and thick denim. Sew a straight line of about 15 cm at your normal stitch length, then a line of zigzag.

Look closely at both sides. Zigzag shows tension faults very clearly: with balanced tension the threads meet at the outer points of each zigzag. Write the dial setting on the fabric in pen so you can compare tests.

| What you see | What it means | What to do |
| --- | --- | --- |
| Bobbin colour dots on top | Upper tension too tight | Lower the upper tension number |
| Upper colour loops underneath | Upper tension too loose | Raise the upper tension number |
| Each colour only on its own side | Balanced | Leave it alone |
| Puckering on light fabric | Tension or stitch length too tight | Lower tension slightly, lengthen the stitch |

Reading a two-colour test seam

## Adjusting the upper tension dial

On most domestic machines the upper tension dial runs from about 0 to 9, with a middle setting of around 4 marked as the standard. Higher numbers tighten the upper thread; lower numbers loosen it. Some computerised machines set tension automatically or through the screen, so check your manual for how yours works.

Change the setting by one step, sew another test line and compare. Small moves are enough: if you find yourself turning the dial to the very top or bottom, go back and look for a threading, needle or bobbin fault instead. Once you find the right setting for a fabric, note it down for next time. Changing fabric, thread or number of layers can each need a small adjustment.

[Compare computerised sewing machines](https://stitchandhem.co.uk/best/best-computerised-sewing-machines)

## When to touch the bobbin case screw

The bobbin case has its own tension, set by a small screw on the spring. Manufacturers set it at the factory, and for normal sewing it rarely needs changing. The upper dial is designed to be the everyday control, so it is the one to use.

If you have rethreaded, changed the needle, cleaned the bobbin area and the stitch still will not balance across the normal range of the upper dial, the bobbin tension may be the cause. Check your manual first, as some makers advise against adjusting it at all, and on some drop-in systems the case is meant to be replaced instead. If your manual allows it, make only a very small turn, a fraction of a turn at most, and test before going further. Mark the screw position first so you can return to it. If it still will not balance, take the machine to a qualified sewing machine engineer rather than turning the screw further.

Note: Switch off and unplug the machine before removing the needle plate or bobbin case. Small bobbin case screws are easily lost, so work over a tray or a light coloured cloth.

## Brand notes and choosing a machine

Janome, Brother, Singer and other makers all use the same principle, though the dial position, numbering and default setting vary by model. If you often search for Janome sewing machine tension problems or similar, the checks above apply equally to every brand. Computerised machines with automatic tension can make everyday sewing simpler; see our guide to [the best computerised sewing machines](https://stitchandhem.co.uk/best/best-computerised-sewing-machines), or [the best sewing machines for dressmaking](https://stitchandhem.co.uk/best/best-sewing-machines-for-dressmaking) if you work with a wide range of fabrics.

## Frequently asked questions

**What number should my sewing machine tension be on?** Many machines mark a standard setting around 4 or 5, which suits general sewing on medium cotton. Treat that as a starting point and test on your own fabric, since the right number varies by machine, fabric and thread.

**Why does my tension keep changing?** It is more likely that the threading has slipped or lint has built up. Rethread with the presser foot up, clean the bobbin area and fit a new needle before changing settings.

**Should I adjust the bobbin tension or the upper tension?** The upper tension, almost always. Bobbin tension is set at the factory. Only consider a very small adjustment if your manual allows it and the upper dial cannot balance the stitch.

**Does stretch fabric need different tension?** Often slightly lower upper tension and a stretch or zigzag stitch help, along with a ballpoint or stretch needle. Test on a scrap of the same fabric first.

## Buying guides on this topic

- https://stitchandhem.co.uk/best/best-computerised-sewing-machines
- https://stitchandhem.co.uk/best/best-sewing-machines-for-dressmaking
- https://stitchandhem.co.uk/best/janome-sewing-machines-compared
- https://stitchandhem.co.uk/best/best-sewing-machines-for-beginners